This invention relates to displays; and, more particularly, to magnetic displays comprising a ferrofluid.
Electro-optic displays are well known. Such displays utilize electric fields, currents and voltages to drive electro-optic media such as liquid crystals; discharge-gases; and, liquid-suspended-needles; flakes and particles. See, for example, U.S. Pat. Nos. 3,674,475 (suspended particle migration display); 3,257,903 (suspended dipole particles) and 3,718,380 (liquid crystal display).
Some activity in magnetic displays has also occurred. See, for example, "A Magnetic-Particles Display", Lawrence L. Lee, IEEE Transactions on Electron Devices, Vol. ED-22, No. 9, September, 1975.
There has also been some activity in which magnetic imaging without toner has been accomplished.
For example, U.S. Pat. No. 3,221,315 to Brown et al. is directed to the utilization of encapsulated ferrofluids in a magnetic recording medium wherein the ferrofluid orientation in the presence of a magnetic field exhibits a variable light-responsive characteristic. In this case, the magnetic recording medium is self-developing in the sense that magnetic marking material need not be employed to present a visible image.
U.S. Pat. No. 3,013,206 to Youngquist et al. discloses a magnetic reader comprising a hollow non-ferromagnetic vessel having a civity field with a suspension of flat, visible, weakly ferromagnetic crystals which orient when suspended in the liquid and in response to a magnetic field.
In new and growing areas of technology, it is sometimes desirable to expand into selectively imagable displays utilizing novel compositions, structure and imaging techniques to provide visible images without hard copy. The present invention is directed to a novel magnetic imaging display.